1,2-Benzoquinone

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1,2-Benzoquinone
Names
Preferred IUPAC name
Cyclohexa-3,5-diene-1,2-dione[1]
Other names
  • ortho-Benzoquinone
  • o-Benzoquinone
  • o-Quinone
Identifiers
3D model (
JSmol
)
ChEBI
ChemSpider
ECHA InfoCard
 100.243.463 Edit this at Wikidata
KEGG
UNII
  • InChI=1S/C6H4O2/c7-5-3-1-2-4-6(5)8/h1-4H checkY
    Key: WOAHJDHKFWSLKE-UHFFFAOYSA-N checkY
  • InChI=1/C6H4O2/c7-5-3-1-2-4-6(5)8/h1-4H
    Key: WOAHJDHKFWSLKE-UHFFFAOYAR
  • O=C1/C=C\C=C/C1=O
  • C1=CC(=O)C(=O)C=C1
Properties
C6H4O2
Molar mass 108.096 g·mol−1
Appearance Red volatile solid
Density 1.424 g/cm3
Melting point 60–70 °C (140–158 °F; 333–343 K) decomposes[2]
Hazards
Flash point 76.4 °C (169.5 °F; 349.5 K)
Related compounds
Related compounds
 1,4-benzoquinone
quinone
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

1,2-Benzoquinone, also called ortho-benzoquinone, is an

ethyl ether. It is rarely encountered because of its instability, but it is of fundamental interest as the parent compound of many derivatives which are known.[3][4]

Structure

The molecule has C2v symmetry. X-ray crystallography shows that the double bonds are localized, with alternatingly long and short C-C distances within the ring. The C=O distances of 1.21 Å are characteristic of ketones.[5]

Preparation and reactions

1,2-Benzoquinone is produced on oxidation of catechol exposed to air in aqueous solution[6] or by ortho oxidation of a phenol.[6]

A strain of the

bacterium Pseudomonas mendocina metabolises benzoic acid, yielding 1,2-benzoquinone via catechol.[7]

Ortho-quinones are widely used in organic synthesis.[8]

Occurrence of ortho-quinones

The oxidation of lysyl side chains is effected in nature by the action of an orthoquinone called lysyl tyrosylquinone.

4,5-Dimethyl-1,2-benzoquinone, also a red solid, is a well behaved synthetic ortho-quinone.[9]

The biological pigment melanin is rich in ortho-quinones.

Finally, the enzyme cofactors tryptophan tryptophylquinone (TTQ), cysteine tryptophylquinone (CTQ), lysine tyrosylquinone (LTQ) and pyrroloquinoline quinone (PQQ) contain the ortho-quinone moiety in their chemical structure.[10]

See also

References

  1. ISBN 978-0-85404-182-4
    .
  2. OCLC 29029713
    .
  3. ISBN 9780470771297
    .
  4. ISBN 9780470771303
    .
  5. doi:10.1039/P29730000476
    .
  6. ^
    PMID 11796071
    .
  7. PMID 16480184
    .
  8. PMID 12379138
    .
  9. doi:10.15227/orgsyn.052.0088
    .
  10. PMID 12785842
    .
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